Ibasso PB-2 First Impression

Here comes the new balanced amp from Ibasso! To counter RSA’s quad-mono SR-71b, Ibasso has created quite a monster portable amp in the form of the PB2. I’m sure you’ve all heard of it: 32 volts of swing and 2.5watts maximum output puts this portable in a desktop amplifier league.

IMPRESSIONS WITH FULL SIZE HEADPHONES Of course the first thing I did when I received the PB-2 was to hook it to a Hifiman HE-6 to see if the rumors are true. Indeed it has enough power to drive the HE-6 to quite a good loudness level, and I’m only using the low-gain setting with volume control at 3pm!

While the PB-2 can never replace the impact and authority of a big desktop amp, the PB-2 can definitely take on a lot of entry level single ended desktop amps. For instance, listening to the HD650 in balanced, the PB-2 was able to grab a good control of the drivers, injecting a good dose of pace and making the HD650 feels lighter and more nimble than it normally is. I think in this sense the balanced drive really helps to pick up the pace of the HD650, as my Grace m902 ($1,500 headphone amp with single-ended headphone out) though having more impact and authority, doesn’t improve the pace of the HD650 as well as the Ibasso PB-2. Now that’s quite a compliment.

IMPRESSIONS WITH CUSTOM IEMSWith custom IEMs like the JH16Pro, the balanced drive gives an instant boost in soundstage size and bass quantity and you get a much bigger sound than you do when driving in single ended. However, I do think that while very impressive in short listening sessions, the balanced drive only increases the phase inaccuracy already inherent in the multi-driver IEM design. The balanced drive also didn’t improve things like articulation, detail extraction, imaging precision, or bass control out of the JH16, and again I will have to go with the Pico Slim or the RSA Shadow for my JH16.

OP-AMPS & BUFFERS Opening the enclosure (Ibasso has supplied the hex key required to open the case), and I’m greeted with two rows of quad opamp arrays. It’s a pretty awesome sight to behold in a portable amp. The layout is very clean and symmetrical, as Ibasso had placed the messy part on the bottom side of the PCB. Ibasso also supplied an extra quad set of BUF634 buffers and an extra quad set of AD797 opamps, as well as dummy boards to bypass the buffer section. In total, you get 16 pieces of opamps/buffers along with the PB2.

Of course this is an incredible opportunity for opamp rolling. The PB-2 comes stock with the OPA604 op-amp and BUF634U buffer. The stock set up is actually quite good and has a very good tonal balance with good vocal presence, full mids and lows. Upon changing the opamp to the AD797, you get better bass control and more lively treble. When used in conjunction with the buffers, I felt that the midrange transition is not very linear when compared to using the OPA604 opamp. I prefer the AD797 without the buffer section, as it gives me the true AD797 sound.

My buddy Neob sent me a pair of dual-channel DIP OPA2111KP op-amps, which he said is a good pairing for the Ibasso P3, and indeed it is a very good opamp for the PB-2 too. The 2111 has a neutral presentation like the stock OPA604, but with a bigger soundstage and a more open sound. The treble is less agressive and also smoother than the OPA604, and so far it is the best match I’ve found for the PB-2. I haven’t quite tested the PB-2 with old time favorites like the OPA627, because I don’t have enough chips to fill in the quad-channel.

The buffer helps to add current to the output, which is useful for hard to drive headphones like the HE-6. But in terms of sound colorations, the buffer adds mid and low body, while lowering transparency. So, if I’m using the PB-2 with the 300 Ohm HD650, I’d rather have the buffer replaced by the dummy adapters as the amp runs cleaner without the buffers. Between the two buffers, the stock BUF634U is more neutral all around, while the DIP-package BUF634P WB (with the brown dale resistor soldered) is the same buffer running in high bandwith mode. The high bandwith BUF634 has 180MHz compared to 30MHz on the plain BUF634. For this reason, the BUF 634P WB is always the better choice for driving current hungry headphones like the HE-6, but keep in mind that battery life will also suffer tremendously (quiescent current averages 15mA vs 1.5mA on the low bandwith mode.)

As a recap, here is a general guide to the opamp and buffer configuration:

If you want a more transparent sound and better texture on the bass areas, take out the buffer section and go with a dummy buffer.

No buffer – Limited current, but still good for HD650, sound is cleaner and more transparent to the actual signature of the op-amp.

These are the opamps and buffers Ibasso included with the PB2. Left to Right: BUF634P (High bandwith 180MHz), BUF634U (Low bandwith 30MHz), Dummy adapter, AD797 (SOIC package), OPA604 (DIP Package).

The default configuration. Opamps are on the top row, buffers on the bottom row. OPA604 (top row), BUF634 (30MHz) bottom row.

The stock opamp OPA604 (top row) with BUF634 (180MHz) bottom row.

AD797 opamp (top row), dummy adapters (bottom row).

Mounting dual-channel DIP op-amps (top row).

COMPARED TO THE PB1Like the PB-1, the PB-2 has a very good build quality. I’m loving the new matt finishing from Ibasso, and I think it really looks good in silver. There are no sharp edges in the housing, finishing quality is very smooth, definitely Ibasso has improved their build quality a lot since the P2 days. I do have to say that the longer enclosure, though understandable given the power output, is a big turn off when I can be using much smaller amps like the Headstage Arrow or the Pico Slim. I think you’ve got to have a real need for the power output of the PB-2, otherwise it will make more sense to go with the other slim amp models. Another thing that’s preferable on the PB-1 is the placement of gain switch. On the PB-2, you need to open up the enclosure to get access to the gain jumpers, where on the PB-1 the gain switches are accessible through the bottom side of the amp.

Compared to the PB-1, the PB-2 has an almost identical sound signature and tonal balance. Ignoring the power output differences, the PB-2 on the stock op-amp and buffer sounds slightly warmer with less aggressive treble and more low end body, while the PB-1 has a better clarity on the treble area. When you take out the buffer and only run it on the stock OPA604 op-amps, then the PB-2 sounds improves the clarity on the treble to match the PB1 while still being warmer and more neutral.

(special thanks to Neob for the PB1 loaner).

Comparison with the PB-1 (top), PB-2 (bottom).

Comparison with the PB-1 (top), PB-2 (bottom).

Comparison with the PB-1 (top), PB-2 (bottom).

The gain jumpers.

END WORDSThroughout my listening time with the PB-2, I almost never see the need to use the mid or high gain level, other than just testing how loud it can drive the HE-6 headphones. But for actual listening, I actually find the low gain to be enough even for the HD650 and the HE-6. With the HE-6, though the voltage swing is plenty, it didn’t quite have the authority to make a slamming bass impact. However, with the 300 ohm HD650, the experience is very enjoyable as the PB-2 is perhaps the most affordable amp I’ve tried with the HD650.

Svfoo123

Anonymous

Hi, I made a short comparison to the Grace m902 in the article:

/While the PB-2 can never replace the impact and authority of a big desktop amp, the PB-2 can definitely take on a lot of entry level single ended desktop amps. For instance, listening to the HD650 in balanced, the PB-2 was able to grab a good control of the drivers, injecting a good dose of pace and making the HD650 feels lighter and more nimble than it normally is. I think in this sense the balanced drive really helps to pick up the pace of the HD650, as my Grace m902 ($1,500 headphone amp with single-ended headphone out) though having more impact and authority, doesn’t improve the pace of the HD650 as well as the Ibasso PB-2. Now that’s quite a compliment./

Likewise the part about pace and the more nimble HD650 also applies when compared to the M-Stage.

George

Anonymous

In a way it’s very close to desktop amps, even in ways that my desktop amps can’t compare.

Please read the passage about the HD650 and the Grace m902 comparison — a lot of single-ended headphone amps will not be able to drive the HD650 with the same pace as the PB-2 in balanced, and this is probably due to the benefits of the balanced drive. But on the other hand, bass impact and slam is not quite close to the powerful desktop amps such as the Grace or even the M-Stage.

George

Mike, have you tried it with the DB1 balanced DAC so far? That would be a fully balanced setup. One head-fi, the word it that the differences with the DB1 and without are more pronounced with the PB2. Le t me know what you think.

George

George

Mike, glad to hear you will be getting an SR71B and comparing all the amps, especially the PB2. You came through yet again! I can can vouch for the SR71B’s strength with the HE6, as I have heard it. I felt it was lacking bass, but I had no prior experience with the HE6 and did not know the source and music etc. The clarity, speed, naturalness, and mids and treble were all fantastic, and I really loved the soundstage and imaging, despite the imaging being pretty inaccurate as you have noted. It was still big and real, which was what I liked.

George

As I said, it was not my music and source, and I had no experience with the HE-6. I am pretty sure the SR71B is not bass light, as all the review I have seen have said so. I am probably going to listen to that combo again next month, and i will let you know what I think.

Anonymous

I ve received the SR71b. The sound reminds me a lot to the Protector. It doesn’t drive the HE6 as loud as the PB2, mostly a function of voltage swing. But I felt that the bottom heavy signature pairs with the HE6 better.

Anonymous

my setup would be macbookpro > DAC > amp > currently using ATH-AD700. Other than that, i’d probably go with iphone > amp > HD-280pro for more portable.

I do have Denon AVR 591 AV receiver if that might be a good source.

I’m currently looking for an upgrade of my ATH-AD700. Not sure which direction yet, but looks like Sennheiser HD598 or HD600 might be a good choice. I own HD555 and it feels that i lack the clarity in it. much prefer the AD700.

March 1, 2011

Anonymous

If I’m not looking for a particular sound, I’d just go with a simple one box set up like the Yulong U100. It sounds great out of the box, and it’s very convenient to use. Unless you have a real reason to go balanced (which I don’t think you need, with the AD700).

Earfonia

Anonymous

FLACvest

Thanks for helping me choose between the D12 Anaconda and the PB2 Pelican. I’m sold on the Pelican now. I was a bit leery of dealing with Balanced and getting stuff recabled, but the quality is obvious in balanced mode per your review and the device looks stunning and is set up very very logically. I’m excited!

Anonymous

Good question! I actually forgot to address those issues in the article. 1. No more hissing sound on the volume knob. However, I do think that this may be a case-by-case scenario, one pot may make the noise, while the next one may not. 2. Of course. Low gain always give the lowest noise floor, blacker background, cleanest separation. High gain gives a slightly more dynamic sound, more punchy, more lively.

Anonymous

Hi Ubik, I can’t quite rank it like that. Amplifiers come with different characteristics, and what you need to do is find a good match with your prefernce and music. Roughly, here is a short guide: PB2 – balanced drive, very powerful, fast paced. Lisa3 – powerful, single ended, mid and bottom end heavy. Pico Slim – good for IEMs, excellent detail and articulation. Alo Rx – grain free, very widesoundstage, lively TTVJ – good detail, clarity, midrange body.

To fully exploit the HD650, you need a good balanced desktop amp like the Beta22.

jeffreyfranz

Anonymous

Indeed it is cost effective. If you’re using the HD650, which is not very current hungry, you can also use the PB-1 as it have enough voltage swing for the HD650. The PB-2 will only give you the benefit of opamp rolling.

jeffreyfranz

Mike, my main interest in either PB1 or PB2 would be to “pick up” and add life to the HD 650s via balanced drive (You said: “injecting a good dose of pace and making the HD650 feels lighter and more nimble than it normally is”). The HD 650 is just too dark for me. I would, however, also want to be able to drive my AKG K701 (60 Ohm), which has a rather opposite signature. All things considered, could you steer me one way or the other? Thanks.

Anonymous

Hi Jeff, The PB-1 and PB-2 has an almost identical sound signature. For the HD650 and the K701, I’d rather use the PB-1 which I find has a cleaner sound stock compared to the PB-2. With the PB-2 you get to do opamp rolling and you have a higher current output, which you don’t need with the HD650 (and probably the K701 too).

If the HD650 is too dark for you, again driving it with a balanced drive is not going to turn it into a brighter headphone. It will make the HD650s’ pace faster, more nimble, less slow, but it’s still primarily a dark headphone.

As for the K701, I haven’t tried it with the Ibassos, but if I’d have to pick, I’d probably use an RSA amp for the K701, simply to add bottom end body.

Anonymous

1) Would the PB1 have enough power to run 600 Ohm DT880’s? PB1 is cheaper (Student budget). 2) Would the sound signature of the PB2 be better suited for DT880’s or the PB1? Is there a significant difference?

eagle1776

So in response to some of your comments… Do the PB1 or PB2 outdo desk amps in the same price range? I understand they don’t have the authority of a >$1000 amp but what about that <$250 range. Someone on Headfi was saying they preferred the PB1 to the Schitt Asgard for the HD600. Is it possible I can choose portability and sound just as good at that price range?

Underpinkmoonlight

Anonymous

It wouldn’t be a bad pairing, but I don’t think you need a separate amp for your B&W P5, let alone something as big as the PB-2. If you want to give the Ibasso a try, the PB-1 should be sufficient. The sound signature is identical to the PB-2 but with slightly less power (still more than enough for your B&W P5).

DT_MS

Anonymous

Hi, I didn’t review the uHA-120 (Lieven did) and so I would answer this based on my experience with the AHA-120 (the bigger version of the uHA-120).

In terms of refinement the JustAudio amp is much superior than the Ibasso. The Ibasso PB-2 however currently ranks as the most powerful portable amplifier in the market (at least the ones I’ve tried). However with the HD650 you don’t really need that much current to begin with and so I don’t think you really need to go with the PB-2. Even something like Ibasso’s own P4 would do a better job with the HD650 since it’s a more refined amp than the PB-2.

Thing is the PB-1 is powerful enough for most orthos, especially the older ones that tend to have smaller drivers. It would be best if you can reterminate the headphone to a balanced plug so you can get the full power output of the amp. The PB-2 is more powerful, but you shouldn’t need it except for things like the HE-6, which the PB-2 still can’t drive adequately anyway. The Cmoy design is quite weak on current so I’m not surprised it distorts your TDS.

Hi Mike, Just got the PB2, had a question? How do I change the gain settings. If you can tell me how to get the highest gain settings as I can barely hear anything from the 600 ohm K141 and T1 with the full volume.

I’m using the same settings you’ve used in the above jumper picture with the only exception that both the right jumper are exactly inverse of the left jumpers. That is the loudest sound I’m apparently getting from the jumper distribution.

Dear MikeI have been reading your articles and really changed my poin of view… thanks to you i now have a better understanding in Hifi stuff.but I still need your opinion regarding things i need to buy. as what I need is mostly to practice on my bass guitar silently, listen music from my iphone 4s.and I already have shure se535 for my daily use.and now i’m searching for a practice headphone that can give deep, low clarity sound of my bass, without a distortion when i slap or picking it.i like to hear and play my bass in these genre: pop, rock, funk, a bit of jazzstill confused with what should I choses to buy I narrowed it down to some from your articles;headphone: HIFIMAN HE-500, sennheiser HD650, and ultrasone pro 900amp : fiio e11 , ibasso pb-1/2 (ready on near store)please help me with this matter.. if you have another recommendation please just tell. dont want to get overpriced nor doesnt find my expectation.thank you

Tim, I’m probably not the best guy to answer this, but if you have a guitar store in your town, it’ll be best for you to stop by and test them out. Personally on the top of my head I’m thinking of monitoring headphones like the Shure SRH-940 or the Beyer DT770.

I finnaly buy the audio technica pro 700mk2 50 years edition (the store clerk persuade me to buy it… ) but turns out it is a good one, suits me.

Also already try the ibasso PB-2 with it. But I kind off not like the combinations between those two. It doesnt add more quality as the PB-2 with other headphones. Can you help me with this matter? Is there any other choice of portable amps? I also try the pico amps but forgot what series. But it also doesnt give much changes on the pro700 quality..